# Open Sentences – Skip Counting 3s, 5s, 6s, 7s, 8s, 9s and 10s | Open Sentences (Addition and Substation) | Real Life Problems and Quantitative Reasoning Primary 3 (Basic 3) Term 2 Week 8

### MATHEMATICS

SECOND TERM

WEEK 8

PRIMARY 3

THEME – ALGEBRAIC PROCESSES

PREVIOUS LESSON –

### TOPIC – OPEN SENTENCES

#### LEARNING AREA

1. Introduction

2. Skip Counting 3s, 5s, 6s, 7s, 8s, 9s and 10s

3. Open Sentences (Addition and Substation)

4. Real Life Problems

5. Quantitative Reasoning

6. Revision and Weekly Assessment (Test)

### LEARNING OBJECTIVES

By the end of the lesson, most pupils should have attained the following objectives –

1. skip Counting 3s, 5s, 6s, 7s, 8s, 9s and 10s

2. find the missing number in an open sentence.

3. identify the relationship between addition and subtraction.

4. solve related quantitative aptitude problems.

### ENTRY BEHAVIOUR

The pupils can count objects, solve simple addition and subtraction.

### INSTRUCTIONAL MATERIALS

The teacher will teach the lesson with the aid of chart containing worked examples on open sentences.

### METHOD OF TEACHING

Choose a suitable and appropriate methods for the lessons.

Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons.

### REFERENCE MATERIALS

1. Scheme of Work

2. 9 – Years Basic Education Curriculum

3. Course Book

4. All Relevant Material

5. Online Information

### LESSON 1 – INTRODUCTION

Skip counting is a method of counting numbers by adding a number every time to the previous number.

For example,

Skip counting by 2, we get 2, 4, 6, 8, 10, 12 and so on.

2

2 + 2 = 4

4 + 2 = 6

6 + 2 = 8

8 + 2 = 10

10 + 2 = 12, and so on.

Skip counting by 3, we get 3, 6, 9, 12, 15, 18, 21 and so on.

3

3 + 3 = 6

6 + 3 = 9

9 + 3 = 12

12 + 3 = 15

15 + 3 = 18, and so on.

Skip counting by 4, we get 4, 8, 12, 16, 20, 24, and so on.

Skip counting by 5, we get 5, 10. 15, 20, 25, 30, and so on.

Skip counting by 6, we get 6, 12, 18, 24, 30, 36, and so on.

Skip counting by 7, we get 7, 14, 21, 28, 35, 42, and so on.

Skip counting by 8, we get 8, 16, 24, 32, 40, 48, and so on.

Skip counting by 9, we get 9, 18, 36, 45, 54, 63, and so on.

Skip counting by 10, we get 10, 20, 30, 40, 50, 60 and so on.

### LESSON 2 – OPEN AND CLOSED SENTENCES

ACTIVITY 1 – INTRODUCTION

Open sentence is a sentence that is unknown to be true or false. For example, 5 + (  ) = 8.

5 + (  ) = 8 is a mathematical statement that contains one blank or unknown variable that can be either true or false depending on what values are used.

5 + 3 = 8 is a closed sentence, it is true.

5 + 2 = 8 is a closed sentence, it is false.

A sentence is a closed sentence is always true (or always false).

A sentence is an open sentence when it is unknown to be true or false. In an open sentence, a symbol or any alphabetical letter can be used as variable.

For example, 5 + (  ) = 8 or 5 + x = 8

ACTIVITY 2 – WORKING EXERCISES ON CLOSED SENTENCES

Indicate True or False for each of the following closed sentences.

1. 6 + 5 = 11

2. 4 + 4 = 14

3. 8 + 0 = 80

4. 5 – 4 = 3

5. 9 + 6 = 16

6. 5 – 3 = 2

7. 9 – 5 = 5

8. 6 – 3 = 3

9. 7 + 4 = 11

10. 11 – 11 = 01

### LESSON 3 – OPEN SENTENCES

ACTIVITY 1 – REVIEW OF OPEN SENTENCES

A sentence is an open sentence when it is unknown to be true or false. In an open sentence, a symbol or any alphabetical letter can be used as variable.

ACTIVITY 2 – OPEN SENTENCES INVOLVING ADDITION AND SUBTRACTION

Examples

1. 5 + (  ) = 8, what number can be added to 5 to get 8?

5 + ( 3 ) = 8

2. (  ) – 3 = 8, what number can be minus 3 to get 8?

( 11 ) – 3 = 8

3. 15 – (  ) = 7, what number can be subtracted from 15 to get 7?

15 – ( 8 ) = 7

4. (  ) + 11 = 19, what number can be added to 11 to get 19?

( 8 ) + 11 = 19

ACTIVITY 3 – WORKING EXERCISE

Find the number presented by (  ) in each of the following:

1. (  ) + 13 = 18

2. 9 + (  ) = 15

3. (  ) – 11 = 7

4. 19 – (  ) = 10

5. 11 + 9 = (  )

### LESSON 4 – REVISION ON OPEN AND CLOSED SENTENCES

ACTIVITY 1 – Indicate True or False for each of the following closed sentences.

1. 6 + 5 = 11

2. 4 + 4 = 14

3. 8 + 0 = 80

4. 5 – 4 = 3

5. 9 + 6 = 16

6. 5 – 3 = 2

7. 9 – 5 = 5

8. 6 – 3 = 3

9. 7 + 4 = 11

ACTIVITY 2 – Find the number presented by (  ) in each of the following:

1. (  ) + 13 = 18

2. 9 + (  ) = 15

3. (  ) – 11 = 7

4. 19 – (  ) = 10

5. 11 + 9 = (  )

### LESSON 5 – ASSESSMENT TEST

As stated in course book.

### PRESENTATION

To deliver the lesson, the teacher adopts the following steps:

1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the pupils some questions;

2. Teacher organizes the pupils in groups or pair depending on the size of the class.

3. Teacher displays charts showing open and close sentences.

4. Teacher leads a group discussion open and closed sentences.

5. Teacher uses the charts and the group’s relevant responses to introduce the lesson.

6. Teacher explains in details using appropriate examples to distinguish between open and closed sentences.

7. Teacher guides the pupils through working examples and appropriate working exercises.

8. Teacher summarizes the lesson on the board with appropriate evaluation.

Pupil’s Activities – The pupils participate actively in the summary of the lesson by responding correctly to most of the questions write as instructed.

### CONCLUSION

To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson.

### NEXT LESSON

Change of Money not Exceeding ₦50 | Addition, Subtraction and Multiplication of Money not more than ₦50 Primary 3 (Basic 3) Term 2 Week 9 Mathematics